A wire line core barrel inner tube assembly having a downwardly facing annular suspension shoulder seatable on a core barrel outer tube landing shoulder, a bypass channel having an upper port above the annular shoulder, a lower port below the annular shoulder, and an axial bore extending between the ports and a ball movable in the bore between a position blocking fluid flow in the bore between the ports and a position permitting such flow through the ports.
It is known to provide an axial bore in a latch body upper section, an axially elongated bore, outer ports opening through the outer circumferential peripheral surface above the maximum diameter part of the latch body and to the bore, inner ports opening through the latch body outer circumferential peripheral surface below the maximum diameter part and the downwardly facing annular shoulder of the latch body, a piston mounted in the bore and resiliently urged upwardly, and a chevron shaped slot in the latch body for receiving a guide member that is joined to the piston. When the guide member is in the upper part of the inclined slot leg, the piston blocks fluid flow through the bore and when in the uppermost part of the vertical leg of the chevron slot the piston permits flow the bore, the piston being movable under fluid pressure from the upper part of the inclined slot leg to the intersection of the slot legs and when the pumping of fluid into the drill, stem stops, the guide member moves to its uppermost position in the vertical leg. However when the guide member is in the uppermost part of the inclined leg and the core barrel inner tube assembly is allowed to free fall under gravity in the drill stem, the rate of descent is very slow as the bypass channel is substantially blocked.
In the prior art, for example see U.S. Pat. No. 3,103,981 to Harper, when the lower port of the bypass channel is at the level of the minimum diameter portion of the hanger coupling (drill stem support shoulder) the fluid pressure at the pumping station increases and than drops as the port passes the minimum diameter portion. At times the operator may not notice the increase of pressure which signals the inner tube assembly is at the bit end of the drill stem. Even if a pressure gauge is provided at the pumping station which is of a type that has a needle which constantly moves with variations in pressure, and a second needle that is moved by the first needle and remains at the highest pressure position, the second needle may be broken off, or there may be significant variations in pressure as the inner tube assembly is pumped down the drill stem and if the operator is not constantly watching the gauage, the operator may not know whether or not the second needle position is a result of the inner tube assembly being moved to be seated on the hanger coupling portion.
In order to overcome problems such as the above as well as others, and to provide a fast descent wire line core barrel inner tube assembly, this invention has been made.